Yup, it's already time for my weekly update.
Actually, nothing has changed. My plant is still growing and gaining weight.
Yesterday, I cleaned the coir with Flora Clean (3ml/l). I used 10 liters cause I suspect that there is a buildup somewhere. The plant lost a few leaves at the bottom but the rest is going well.
Watering remained the same—every day for 4 minutes. 3 waterings usually take 10 liters of water. It turns out that my system is not reversible as I've planned from the beginning. But I doubt that I'll use the reversible system next time, it doesn't suit my methods of global watering.
Unfortunately, my new system cannot flush the plant by itself. Next time, I'm planning to do it myself once a week, probably with Flora Clean. Anyway, it is a thought for the next growing. I won't change anything right now—it's harvest time soon and I'm afraid to ruin it.